1. Field of the Invention
This invention relates to a micro-displacement type information detection probe device utilizing the reverse piezoelectric effect for positional determination of a probe for the scanning tunneling microscopy, etc., and a scanning tunneling microscope, an atomic force microscope and an information processing device having such a device mounted therein.
2. Related Background Art
In recent years, the recording capacity of data in recording devices tends to become increasingly larger. In this tendency, it is essentially required that the size of the recording unit should become increasingly smaller and its density still higher. For example, in a digital audio disc for optical recording the size of the recording unit approaches even to about 1 .mu.m.sup.2.
On the other hand, recently, scanning tunneling microscopy (hereinafter abbreviated as STM) by which the electron structures of the surface of substance and the vicinity thereof can be directly observed has been developed [G. Binnig et al., Phys. Rev. Lett. 49, 57 (1982)], whereby it has become possible to measure real space images with high resolving power, irrespectively of whether the substance may be either single-crystalline or amorphous. Moreover, since it has the advantage that observation can be made at low power without giving any damage by current to the medium, and further since it can be actuated not only in a super-high vacuum but also in air or in solution and used for various materials, a wide scope of applications has been expected.
The STM utilizes the phenomenon that when a probe of a metal (probe electrode) and an electroconductive substance are approached to a distance of about 1 nm (10 .ANG.) with application of a voltage therebetween, a current will flow between them. The current is very sensitive to the distance change between them, and the surface information of the real space can be obtained by scanning the probe so as to keep the current or the average distance between them at a constant level. In this case, the resolving power in the intraplanar direction is 1 .ANG. or more.
By applying the principle of STM and using a material having a memory effect for switching characteristics of voltage and current as the recording medium, such as thin film of .pi.-electron type organic compounds, chalcogenides, etc., information recording with a recording unit of 0.001 .mu.m.sup.2 or less is possible.
On the other hand, atomic force microscopy (hereinafter abbreviated as AFM) observes the three-dimensional shape of a surface with a resolving power of nanometer or less by detecting conversely the force from the warping amount of a cantilever (elastic member) supporting a probe approaching a distance of 1 nanometer or less to the sample surface by receiving the force acting between the sample and the probe, and scanning the probe on the sample surface while controlling the distance between the sample and the probe so as to make the force constant [Binnig et al, Phys. Rev. Lett. 56 930 (1986)]. In such AFM, the sample is not required to have electroconductivity as in scanning tunneling microscopy (STM), and insulating materials, particularly semiconductor resist surface or biological polymer, etc. can be observed on atomic-molecular order, and therefore wide applications have been expected.
Also, for performing recording and reproduction of high density by use of the above recording medium, a large number of devices have been proposed. For example, in a device disclosed in Japanese Laid-open Patent Application No. 62-281138, a converter, a probe for performing recording and reproduction of information and a probe driven mechanism for controlling the distance between the recording medium and the probe are integrally formed on a silicon chip by use of the photolithographic technique to effect integration of the recording head.
Thus, when the integrated recording head is set in a recording and reproduction device of high density, since the recording area occupied by one recording head is on the .mu.m order, it has been required that hundreds to thousands of recording heads should be prepared, and further arranged to the form capable of relative movement on the order of mm between the recording medium and plural recording heads, thereby enhancing recording capacity or recording speed.
However, when hundreds to thousands of recording heads are prepared and placed in the vicinity of the recording medium, and the recording medium and the recording head are relatively moved on the order of the mm, the following problems will ensue:
1) The distance between the recording medium and the recording probe set at the tip end of recording head is as short as several nm. In order for the recording head to follow the recording medium under this state, since the deviation amount of the recording head is about 1 .mu.m, the undulation or slope of the recording medium and the substrate must be suppressed within about 1 .mu.m.
2) The recording medium and the substrate have also an unevenness of nm period formed during preparation of the recording bit or the substrate, in addition to large undulations of several .mu.m period. When such recording medium and recording head are relatively moved by several mm, the recording head is required to follow both the unevenness of nm period and undulation of .mu.m period. Therefore, if it is intended to follow the unevenness of nm period under the state where the undulation of .mu.m period can be followed, it is difficult to increase the device speed in relationship with the resonance frequency.